Invert emulsion well fluid



United States Patent 3,127,343 INVERT EMULSIGN WELL FLUID William A.Reddie and Charles 0. Brandi-ant, Houston, Tex., assignors to MagnetCove Barium Corporation, Houston, Tex.

No Drawing. Filed July 28, 1969, Ser. No. 45,819 16 Claims. (Cl. 2528.5)

This invention relates to improvements in invert emulsions useful inwell operations. In one aspect, it is an improvement in a method forproducing invert emulsions, in another aspect it relates to improvedconcentrated materials useful in the production of such emulsions and instill another of its aspects it relates to an improved process forconducting well operations.

In the drilling and treating of wells, invert emulsions frequently areused. For example, in rotary drilling of oil Wells, completion of wellsin oil or gas bearing sandstone strata, and in work-over of such wells,invert emulsions supply the solution to a great many problems.Penetration of hydratable shales is easily accomplished by the use of aninvert emulsion drilling mud without difliculty due to hydration.Completion of a well in a gas or oil bearing sand which is easilydamaged by water, can be accomplished safely with an invert emulsiontype of drilling fluid, as these do not damage the productivity of aformation as an aqueous or oil-in-water emulsion type of mud frequentlydoes. The use of invert emulsions in well completions also enables rapidand easy operation and will permit evaluation of the formation not onlymore quickly but more accurately.

In the work-over operation on many oil wells, aqueous drilling muds ormuds of the oil-in-Water type are not at all satisfactory. For example,work-over of wells of the Pennsylvanian Age Sands of Central. Oklahomaoften cannot be carried out successfully by the use of an aqueousdrilling fluid. Water block of the fine pores of these sands maycompletely destroy the productivity of a Well.

The use of oil base muds for well completion and workover in locationswhere aqueous base muds cannot be used has been quite common, but oilbase muds are quite expensive to prepare. A great deal of the cost ofthe drilling fluid may be saved by the use of an invert emulsion type ofmud in which water phase is dispersed as an oil phase. The oilordinarily used is crude oil, or one of the cheaper refined oils such asdiesel oil. Many types of oils may be used but the lower priced oils aremore practical.

An invert emulsion type of mud must have thermal stability up to atleast 250 degrees F. to be practical for use in deep wells, .and theinvert emulsion must be compatible with the usual weighting materialssuspended in the mud in quantities to give controllable densities up toabout 18 pounds per gallon; it should have very low filter loss and anyfiltrate formed should consist only of oil; it must be resistant tocontamination encountered in passing through salt or anhydrite strata;it should be easily prepared with equipment ordinarily present at adrilling rig and it should have satisfactory viscosity and gel strengthwhether prepared with salt water or fresh water.

It has been very difficult to prepare invert emulsions ice having all ofthe required properties; or to prepare concentrated materials for mixingwith water and oil at a well site to yield an invert emulsionconsistently having the above outlined proper-ties. One of the greatestdificulties encountered results from the fact that invert emulsionsfrequently require a very high degree of shear for their preparation.Their production from concentrated emulsifying materials, oil and wateris difficult using the mud machinery commonly available at a drillingrig.

'It is an object of this invention to provide an invert emulsion wellfluid which is easily formed by the use of equipment ordinarily presentat a drilling rig and which does not require excessively high degree ofshear for its formation.

Another object is to provide concentrated emulsifying materials whichmay be mixed with oil and water at a well head to provide a drillingfluid of desirable rheological properties without the necessity forspecial mixing equipment.

Another object is to provide an improved invert emulsion drilling fluidwhich is stable in the presence of hydratable clays and other earthsolids.

Another object is to provide a well fluid of an invert emulsion typewhich is stable at temperatures above 250 degrees F. under highpressure.

Another object is to provide an improved invert emulsion drilling fluidwhich has very low fluid loss and which does not cause water block ofoil bearing sands.

Another object is to provide an improved invert emulsion drilling fluidhaving high lubricity which results in. a high rate of bit penetrationand long life of bit bearings.

Another object is to provide two concentrated materials for use informing invert emulsions; namely, a liquid concentrate for mixing withoil and a free flowing solid concentrate to complement the liquidconcentrate in forming an invert emulsion well fluid.

Another object is to provide an improved process for the production ofan invert emulsion type of Well fluid.

Still another object is to provide an improved method for carrying outwell operations in which water block of oil or gas bearing strata isprevented and hydration of clays and earth solids is largely eliminated.

Another object of the invention is to provide an invert emulsion wellfluid which is stable in the presence of large proportions of salts suchas sodium chloride, calcium sulfate, etc.

Another object is to provide a well fluid having low solids contentcombined with satisfactory rheological properties.

Another object is to provide a well fluid which does not penetrateformations being drilled to any substantial extent and which may be usedin core drilling to recover cores substantially in native state.

Other objects, advantages and features are inherent to the invention andwill become apparent upon a consideration of the written specification,and the claims, herein contained.

We have found that the ease of forming an invert emulsion, using apolymerized polybasic fatty acid pitch as a primary emulsifier, isgreatly increased when an ethylene oxide adduct of pitch is used withthe pitch in proportion from to 75 percent, or preferably from to 50percent of the total quantity of untreated pitch and adduct. This adductis prepared by adducting a polymeriz d polybasic fatty acid pitch withfrom 25 to 75 percent, preferably about to 60 percent of its weight ofethylene oxide, by a well known reaction to be described later.

Although an invert emulsion is easily formed by the use of pitch andadduct, the solids supporting ability of the emulsion is very poor andaddition of a basic magnesium compound in quantity to form magnesiumsoap by reaction in situ with the pitch, does not eliminate thisdisadvantage. However, we have found that the ease with which invertemulsions are formed by the use of pitch and adduct is retained, and thepoor stability of solids is corrected when tall oil to the extent ofabout 6.05 to 0.=l of the total weight of pitch and adduct is added withor incorporated in a pitch-adduct mixture. kpparently the concentrationof free fatty acids in the ixture is critical, and this proportion oftall oil furnis es sufficient free fatty acid to bring the fatty acidcontent of the pitc i-adduct mixture into the critical range.

Also, we have found that small amounts of a mixture of attapulgite and aquaternary ammonium surfactant incorporated in these emulsions isespecially effective for enhancing weight supporting power of the invertemulsions prepared by use of the pitch-adduct-tall oil mixture. We havefound that an attapulgite-quaternary ammonium surfactant mixture,suitable for use in the emulsions, may be prepared by merely mixing theattapulgite and surfactant intimately, omitting the customary steps ofsuspending the attapulgite in water, settling out grit, acidifying thesuspension, adding surfactant, drying the suspension, and grinding theresulting product.

The present invention contemplates the production of invert emulsiontype of well fluids by incorporation of a polymerized polybasic fattyacid pitch, tall oil, and the ethylene oxide adduct of pitch in an oilbase for a well fluid emulsion. We prefer to mix water and oil basecontaining these materials and to agitate the mixture until it isemulsified. A basic magnesium compound, selected from the groupconsisting of magnesium oxide, magnesium hydroxide and magnesiumcarbonate; and a mixture of attapulgite with quaternary ammoniumsurfactant, preferably prepared by intimately mixing the attapulgite andthe surfactant as in a muller, are added as the emulsion forms. Theabove sequence of steps is usually found to be the most convenient,although addition of the in gredients to the emulsion may be carried outin any desired sequence. The quaternary ammonium surfactant, attapulgiteand the magnesium compound are used in the preferred ratio of about 1part by weight of quaternary ammonium surfactant to about 4 to 8 partsof attapulgite and about 18 to 20 parts of basic magnesium compound,magnesium oxide being the preferred basic magnesium compound. The totalquantity of magnesium oxide used is at least sufficient to formmagnesium soaps with all free fatty acids present in the polymerizedpolybasic fatty acid pitch-adduct-tall oil mixture.

This invention also contemplates the preparation of concentratedmaterials for use in forming invert emulsions. It is preferred that twotypes of concentrates be prepared for this purpose; namely, an oilsoluble liquid containing the polymerized polybasic fatty acid pitch,the pitch-adduct and tall oil in a solvent, and a concentratedfree-flowing powder containing the quaternary ammonium surfactantabsorbed on the surface of the attapulgite mixed with magnesium oxide.

For example, the liquid concentrate may be prepared by mixing thedesired portions of polymerized polybasic fatty acid pitch, adduct, talloil, and a heavy aromatic naphtha or a fraction recovered by solventrefining of ilubricating oil, in quantities sufficient to maintain thepitch, adduct and tall oil in solution.

One preferred formulation of such a liquid concentrate (hereinafterreferred to as Concentrate A) is prepared as follows:

Concentrate A Percent Polymerized polybasic fatty acid pitch 33Pitch-ethylene oxide adduct 25 Crude tall oil 3 Heavy aromatic naphtha39 These materials may be merely agitated until a solution results. Thetime required for solution may be reduced and uniformity of product ismore easily attained by the use of moderate heat in preparation of thesolution. A temperature in the range from to degrees F. is preferred forthis use.

A preferred formulation for a free flowing powder for complementary usewith Concentrate A (hereinafter referred to as Concentrate B) isprepared as follows:

Concentrate B- Percent Quaternary ammonium surfactant 7 to 8 Attapulgite(approximately) l5 Magnesium oxide (approximately) 77 *50% solution inisopropyl alcohol.

The mixing of the materials to produce a free-flowing powder(Concentrate B) is best carried out by intimately mixing a quaternaryammonium surfactant with attapul gite, and adding the required amount ofmagnesium oxide. This operation is best conducted in a muller, althoughany similar device may be used which is capable of thoroughly mixing thematerials. It is preferred that this material be passed through a lightgrinding step in order to eliminate lumps which may have formed duringthe mixing step. The resulting mixture is a dry, free-flowing powderwhich can be easily handled.

For making up an emulsion for well fluid use, we prefer to use theconcentrates as set forth above in proportions depending upon theservice for which the well fluid is to be used. The service may bedivided roughly into three categories; mild service, medium service orsevere service. The service classification depends primarily upon thedegree of heat, the degree of contamination by salts and hydratableearth solids normally expected to be encountered, and the amount ofweighting material to be suspended in the emulsion.

When the well fluid is to be used in mild service, it is preferred thatabout 15 to 20 pounds of the above Concentrate A per barrel of wellfluid be used, and that about 1 to 5 pounds per barrel of well fluid ofthe Concentrate B be used. For medium service, it is preferred that thesame proportion of Concentrate A be used and the proportion ofConcentrate B be increased to about 6 to 12 pounds per barrel offinished fluid. When severe service is expected, we prefer to use fromabout 17 to 25 pounds of Concentrate A per barrel of well fluid andabout 13 to 20 pounds per barrel of Concentrate B.

An emulsion prepared as described above, either by use of Concentrates Aand B, or the ingredients thereof added separately or in other mixtures,is an excellent well fluid of low solids content and low density.Weighting materials, such as barium sulfate, lead sulfide, or ironoxide, may then be added to the emulsion to give the density desired.Invert emulsions prepared in this manner are capable of suspendingweighting materials in quantities to give the finished well fluiddensities up to 18 pounds per gallon or more if desired.

The ordinary aqueous well fluids, prepared by dispersion of clays,weighting materials and other conventional substances in water, can beused for the aqueous phase of the emulsion instead of clear water ifdesired. An aqueous drilling mud which has been used to drill down to adepth approaching that at which an oil-bearing sand is normally expectedto lie, may thus be used in this emulsion, but it is preferred to useclear water to form the aqueous phase, because there is less settlingwhen the emulsion is prepared before the Weighting materials, clays,etc. are added.

The proportions of oil and water that may be used in the preparation ofthe well fluid of this invention are quite wide. The finished invertemulsion may contain from 10 to 90 percent by volume of water and from90 to 10 percent of oil, but we prefer to use proportions within theranges of 30 to 70 percent of water and 70 to 30 percent of oil. In mostcases, it is preferable to keep the ranges of both water and oil withinthe limits of about 40 to 60 percent by volume since these limits permitthe dilution of emulsion with either of the major constituents withoutseverely upsetting the rheological properties of the emulsion.

The water used in preparing the invert emulsion may be of almost anytype which is readily available at the drilling site or well location.It may contain small quantities of various salts, such as are found inthe water supplies of most cities or in the water of rivers or lakes,and may even be saturated with sodium chloride. In fact, the desirableproperties of these invert emulsions fre quently are improved by theaddition of sufficient salt to saturate the aqueous phase. Sea water,oil field brines or water containing substantial amounts of gypsum mayalso be used in this preparation.

As stated above, the quantity of water which can be used in theformation of an invert emulsion may be as high as 90 percent. However,as the water concentration exceeds 70 percent, the invert emulsion tendsto become less stable and more prone to flip into an emulsion of anoil-in-water type. These emulsions also tend to be less stable todilution by water entering the well from water-bearing stratapenetrated. It is therefore often preferable that an upper limit ofabout 60 percent by volume of water be used in the emulsion. As thewater content of the emulsion decreases below 30 percent, the viscosityand gel strength of the emulsion may also decrease to a point that itmay be necessary to add gel strength and viscosity increasing materials,preferably water or oil of greater viscosity, to maintain desirablerheological properties in the emulsion.

The density desired in the invert emulsion will partially determine theparticular water concentration to be used. As increased amounts ofweighting materials are added, water concentration should be decreasedto avoid excessive thickness of the fluid. Emulsions of water content inthe range from about 40 to 60 percent, or even more desirable about 50percent, will support large quantities of weighting materials and may bediluted with either water or oil from formations penetrated, withoutincreasing or decreasing the water content to any undesirable extent.

Either refined or crude oils may be used as the oil phase of theseemulsions. Such refined materials as diesel oil or fuel oil aresubstantially free from the lighter hydrocarbons and do not contain thede-emulsifiers which are frequently found in crude oils. It is preferredthat the more inexpensive refined oils be used for this purpose.

The volume of oil used in these emulsions is that which is required tocomplement the volume of water set forth above. The oil proportion issimply the difference between the proportion of water expressed asvolume percent and 100 percent.

The emulsions may contain about to pounds per barrel of polymerizedpolybasic fatty acid pitch, preferably about 5 to 8% pounds per barrel,together with about /2 to 15, preferably about 3 to 6 /2 pounds perbarrel of an ethylene oxide adduct of pitch. The adduct is present inproportion amounting to 5 to 75 percent by weight, preferably 25 to 50percent, of the total quantity of pitch and adduct. Tall oil is presentto the extent of about 0.4 to 1.5, preferably about 0.4 to 0.75

pounds per barrel and in proportion of about 5 to 10 percent, preferablyabout 5 percent of the total weight of pitch and adduct.

A basic magnesium compound selected from the group consisting ofmagnesium oxide, magnesium hydroxide and magnesium carbonate, preferablymagnesium oxide, is present to the extent of 0.75 to 30.0, preferablyabout 0.75 to 15.5 pounds per barrel, and in quantity at leastsuflicient to form magnesium soaps with the free fatty acids present. Aquaternary ammonium surfactant, preferably selected from a group to bedescribed later, in amounts from about 0.03 to 1.6, preferably about0.035 to 0.8 pounds per barrel, adsorbed on about 0.15 to 6.0,preferably about 0.15 to 3.0 pounds of attapulgite per barrel is alsopresent.

We have found that invert emulsions of this type have two remarkablyenhanced advantageous properties, in addition to weight supportingpower, viscosity and gel strength, desirable in well fluids. These twoproperties are high lubricity and such great stability under theconditions of shear and pressure encountered in actual drillingoperations that there is substantially no penetration of fluid into aformation being drilled. For example, in actual core drilling operationson easily permeable strata, cores were recovered in substantially nativestate which enabled accurate determination of water content andcomposition of cores. In actual drilling operations high rates of bitpenetration have been achieved, together with unusually long life ofbits and bit bearings.

We do not know the exact reasons for the great enhancement of these twodesirable properties, but assume that the high lubricity results fromthe presence in the fluid of grease forming materials such as magnesiumsoaps in particularly desirable proportions. Under the conditions ofshear and pressure encountered in actual drilling operations, thepenetration of fluid into the surrounding formation is less than thatwhich might be expected from laboratory fluid loss determinations onsamples of the freshly prepared emulsions.

The polymerized polybasic fatty acid pitch used in the emulsions can bedescribed as a polybasic fatty acid polymer resulting frompolymerization as by heat treatment, of unsaturated (fatty acids whichhave from 12 to 24 carbon atoms per molecule. The resulting polybasicfatty acid polymer comprises at least 30 percent of either the dimers ortrimers which have 24 to 28 or 36 to 72 carbon atoms per molecule,respectively, and are respectively di and tri basic.

Mixtures of dimers and trimers also can be used, such mixtures havingpolymers containing about 24 to 72 can bon atoms per molecule. Among theunsaturated fatty acids which may be polymerized by heat to provide thepolymers for the emulsion linoleic, oleic, erucic, linolenic,isolinolenic, eleomargaric, and eleostearic acids, and mixtures thereofmay be given as examples. While these polymers can be prepared fromreasonably pure unsaturated fatty acids, or mixtures thereof, polymersprepared from pure acids are quite expensive and usually will not beused for economic reasons.

The starting materials for polybasic fatty acid polymers which aresufficiently cheap to permit their use in well fluids ordinarilycomprise various natural vegetable and animal oils and fats which arerich in unsaturated acids, such as cottonseed oil, corn oil, soy beanoil, linseed oil, and tung and rape oils. These naturally occurring oilsalso contain a great many other materials such as sterols, hydrocarbons,alcohols, aldehydes, ketones and saturated fatty acids, in addition tothe unsaturated fatty acids, but are characterized in that they containmore than 30 percent of unsaturated fatty acids having from 12 to 24carbon atoms per molecule.

The term polymerized polybasic fatty acid pitch used throughout thespecification and claims, will refer to polymerized polybasic fatty acidpitches derived from such naturally occurring materials, containingpolymerized 7 fatty acids in admixture with congeneric substances insuch proportions that the polymers will constitute at least 30 percentof the mixture by weight. This mixture should be substantially free fromor low in rosin acids, such as occur in tall oil, to avoid the knowndisadvantages of tall oil emulsions.

Because of ready availability and low cost, We prefer to use thepolybasic fatty acid polymers in the form of a vegetable pitch orlinseed pitch, the latter to be distinguished from linseed oil in thatlinseed oil is an ester and not a polymerized fatty acid. The vegetablepitches commonly available on the market and suitable for use in thisinvention are ordinarily known in the trade as vegetable pitch, butmight also be termed vegetable oil fatty acid pitches. They are sticky,viscous, dark brown materials, usually produced from cottonseed, corn orsoy bean oils. These pitches always contain other materials derived fromthe vegetable oil used as a starting material.

In one process for producing commercial vegetable pitches, a crudevegetable oil is treated with aqeuous caustic solution to convert freefatty acids and glycerides of fatty acids into soap. The complete volumeof reaction products, called raw soap stock, consists of soap, oil andnon-glyceride materials. The raw soap stock is treated with sulfuricacid or other mineral acids to convert soaps into free fatty acids.

The product called acid soap stock, consists of fatty acids, oil andnon-glyceride materials, and the term oil being used by themanufacturers to designate fatty acid triglycerides.

The vegetable oil, acid soap stock or a mixture of both, is passedthrough a high pressure continuous splitter. In the splitter, thematerials are intimately mixed with water and steam at about 500 degreesF. and about 760 p.s.i. The water reacts with the glycerides to formfree fatty acids and glycerine, which are separated. The resulting crudefatty acid fraction contains about 2 percent unsaponifi-ables, withabout 4 percent of glycerides and about 94 percent of free fatty acids.This fraction is then fed into a continuous fractionating still whereapproximately 80 percent of the total material is distilled off overheadas fatty acids, while the remainder is continuously removed from thebottom of the still as stillbottom vegetable residue. The distillationusually is conducted under a pressure of about 2 to 50 mm. of mercury attemperature up to about 510 degrees F., with a small percent of steambeing injected into the base of the distillation column used. Theaverage time the residue is subjected to these conditions is about fourhours. Cottonseed oil, corn oil, and soy bean oil, are the principaloils treated by this process. Either a mixture of these oils or any oneof them may be used as a starting material in the process justdescribed, and accordingly, the stillbottom residue will be derived fromone or more of the oils. It is common practice to use a mixture ofstillbottom residues of these oils as a feed material for the productionof vegetable pitch, although a residue from any one or any combinationof them can be fed separately to produce its corresponding pitch.

The various vegetable pitches are produced by further stripping theindividual or the composite stillbottom vegetable residues in a pitchstill under a pressure of about 2 to 5 mm. of mercury, and at atemperature of about 480 degrees F. for approximately eight hours. Thisstripping is continued for removal of the lighter overhead productsuntil the pitch or stillbottom has the desired specifications. it isquite common to produce vegetable pitches having a viscosity of 9 to 19seconds at a temperature of 165 degrees C. in a Zahn G5 cup. A lighterpitch may be obtained by stopping stripping while the stillbottomproducts have a viscosity of about 8.5 to 10 seconds at a temperature of125 degrees C. in a Zahn G-S cup.

Since corn, cottonseed and soy bean oils contain relatively largeportions of unsaturated fatty acids, and these fatty acids are known topolymerize under prolonged eating, still residues, as described above,will contain 30 percent or more of polybasic fatty acid polymers.

Other methods are known for polymerizing unsaturated fatty acids, suchas heating the original oils in the presence of a catalyst, air blowingthe oils, or heating the oils without a catalyst; all of such methodsbeing well known to those skilled in the art.

A vegetable pitch may be produced by any of the above polymerizingmethods, and the invention is not limited to any one particular type ofvegetable pitch. One type of vegetable pitch suitable for use in thisinvention is sold on the market with following specifications:

Unsaponifiable matter l5 Softening point, ball and ring 55 C.

Acid value 55 (4565). Saponification value 130 (120-135). Iodine value(70-90). Color (Barrett) 18.

Free fatty acids 27% minimum.

Triglycerides, anhydrides and lactones 40% minimum.

This table is given merely as an example of one commercially availablevegetable pitch useable in our emulsions. In general, it may be statedthat any vegetable pitch or polymerized polybasic fatty acid pitch whichcontains at least 30 percent of polymerized polybasic fatty acids, andhas an acid value of at least 23 percent may be used in this emulsion.Pitches having a free fatty acid content of about 26 to 28 percent arereadily available on the market.

Many vegetable oils, other than corn, cottonseed or soy bean oils, canbe treated by the process as outlined above to give a vegetable pitchwhich is useable in this invention. A linseed pitch may be made bytreating linseed oil in the manner described above, or linseed oil couldbe mixed with any of the vegetable oils to give a vegetable pitch whichwould be suitable for use in this process.

The amount of the polymerized polybasic fatty acid pitch used in forminginvert emulsions of the present invention will be dependent upon severalfactors. As for example, when the water content of the finished emulsionis increased, or when the quantity of the weighting materials to beadded is increased, it is usually desirable to increase the amount ofpitch and pitch-adduct.

The vegetable pitch-adduct used with this process is made by adducting avegetable pitch as described above, with about A to (preferably about/t) its weight of ethylene oxide, in a conventional manner.

In this process, a vegetable pitch or other polymerized polybasic fattyacid pitch is dissolved in a sufiicient quantity of suitable solvent torender it fluid. Heavy aromatic naphthas are suitable solvents for usein the reaction. The pitch solution is introduced into an autoclave orother suitable pressure vessel, and the desired amount of ethylene oxideis run in. The reaction mixture is agitated at elevated temperature andpressure until reaction is complete.

In the resulting adduct, the ethylene oxide is added to the oil solublefatty acid molecule in the form of chains, such as O(CH -CHO) H. Theeffect of these side chains of ethylene oxide is to render the insolubleheavy molecules of polymerized fatty acid at least partially watersoluble. These adducts presumably contain ethylene oxide chains unitedto the carbon chain through ether linkages. Other materials present inthe vegetable pitch may also enter into this reaction and take up a partof the ethylene oxide.

Since the exact composition of each of these pitches is variable andunknown, the composition of the product also is variable and unknown andthe adduct can be defined only by its method of manufacture. Theadduction of the vegetable pitches with about A to preferably about 40to 60 percent of their weight of ethylene oxide gives the desiredproperties of solubility and emulsifying 9 power. The use of adduct withvegetable pitch as a primary emulsifier adds spontaneity and ease ofemulsification.

Another material used in the preparation of these emulsions is thecommon crude tall oil of commerce. Tall oil, in admixture with vegetablepitch and vegetable pitch adduct in proportions of about to 10 percent,preferably about 5 percent of total weight of pitch and adduct, willenable the suspension of large quantities of solids in the emulsion.

The quaternary ammonium surfactants used in these emulsions arequaternary ammonium salts derived from long chain fatty acids preferablyhaving from 8 to 18 carbon atoms in the fatty acid chain. The termquaternary ammonium surfactan is used in a limited sense in thisspecification to mean a salt of a tetra alkyl substituted ammoniumradical in which at least one of the alkyl groups is a hydrocarbonresidue of a fatty acid having from 8 to 18 carbon atoms per molecule.Such quaternary ammonium salts may be prepared by reacting any suitableacid, such as acetic, hydrochloric, sulfuric, oxalic and adipic acids,with a long chain fatty acid amine, or by reacting a long chain fattyacid amine with methyl chloride and treating the product with an alkalihydroxide.

A preferred group of quaternary ammonium surfactant which is readilyavailable on the market consists of lauryl trimethyl ammonium chloride;palmityl trimethyl ammonium chloride; coco trimethyl ammonium chloride,which is a mixture of quaternary ammonium chlorides derived from coconutoil fatty acids containing 8 to 18 atoms in the carbon chain in which Cfatty acids predominate; monotallow trimethyl ammonium chloride in whichthe fatty acid chains contain approximately 70 percent of C fatty acidsand 30 percent of C and have an average molecular weight of about 364;dicoco dimethyl ammonium chloride derived from fatty acids normallypresent in coconut oil, having fatty acid chains containing from 8 to 18carbon atoms with C fatty acids predominating and an average molecularweight of about 432; dihydrogenated tallow dimethyl ammonium chloridewhich contains about 70 percent of C and about 30 percent of C fattyacids, with an average molecular weight of about 570; tricaprylylmonomethyl ammonium chloride which is sold commercially with carbonchains from C to C with C acids predominating, and of average molecularweight of about 442; myristyl trimethyl ammonium chloride;oleyl-lineoleyl trimethyl ammonium chloride; stearyl trimethyl ammoniumchloride; dimyristyl dimethyl ammonium chloride; and distearyl ammoniumchloride.

An especially preferred quaternary ammonium subfactant of the abovegroup is coco trimethyl ammonium chloride, since the combination of thismaterial with a small amount of attapulgite usually gives the highestdegree of weight supporting power to the emulsion.

While the specific quaternary ammonium surfactants given as examplesabove are all methyl, dimethyl or trimethyl ammonium chlorides, it isnot intended to limit this invention to these particular materials. Oneor more ethyl groups may be substituted for one or more methyl groups,or morethan one fatty acid chain may be present in the quaternaryammonium surfactant. The specific examples given above refer merely tomaterials which are now easily available on the open market.

The magnesium oxide used in this concentrate may be of any finelypowdered material commonly available on the market, but we have foundthat a synthetic magnesium oxide having a bulk density of a range from20 to 25 pounds per cubic foot and an iodine value in the range from 1to 14, gave somewhat superior results when used in this concentrate.

In the preparation of our emulsions, we prefer to add from about 5 to 8%pounds of a vegetable pitch and about 3 to 6% pounds of vegetable pitchadduct with about 0.4 to 0.75 pound of tall oil per barrel of finishedsolution to the oil to be used therein. These ingredients may be addedin any order, but it is preferred to add them as described inConcentrate A, or similar concentrate, for ease in operation. The oilused in this preparation is a petroleum oil, preferably diesel or fueloil, but crude oil may be used if desired. The oil and water are thenagitated until an emulsion is at least partially formed.

The preferred preparation further contemplates the addition of about0.034 to 0.4 pound of cationic surfactant per barrel of finishedemulsion, adsorbed on about 0.15 to 3 pounds of attapulgite in admixturewith about to 15 /2 pounds of magnesium oxide, preferably added asdescribed in Concentrate B, after the emulsion begins to form althoughit is possible to add the materials to the emulsion at any desired time.

We prefer to control the quantities of emulsifying and stabilizingmaterials within the range given above according to the severity ofconditions expected in the particular well operation in which theemulsion is to be used. When the conditions are expected to be mild, weprefer to prepare an emulsion using the following formulation:

When conditions of medium severity are expected, the preferredformulation will include:

Lb./bbl. Pitch 5.0 to 6.66 Tall oil 0.43 to 0.59 Adduct 3.75 to 5.0Quaternary ammonium surfactant 0.2 to 0.4 Attapulgite 0.8 to 1.8Magnesium oxide 4.0 to 9.25

For use under severe conditions of heat, contamination by salts or earthsolids, and heavy loading with weighting materials, we prefer to preparean emulsion containing the formulation as follows:

Lb./bbl. Pitch 5.6 to 8.25 Tall oil 0.54 to 0.75 Adduct 4.25 to 6.25Quaternary ammonium surfactant 0.4 to 0.75 Attapulgite 1.8 to 3.0Magnesium oxide 9.25 to 15.5

In all cases, We prefer to mix the quaternary ammonium surfactantintimately with dry attapulgite prior to introducing them into theemulsion or mixture. We have found that such mixing results insufificient adsorption of the surfactant on the attapulgite to enhancethe weight supporting power of these emulsions greatly, although thesurfactant and attapulgite are inefiective for such use in otheremulsions when merely mixed dry.

For use when a heaving shale, salt bed, or stratum of easily hydratablematerial is to be penetrated, a saturated salt water is preferred,although any type of water which is readily available is useable in theemulsion. Weighting materials may be added to give any required density.These weighting materials may be either barium sulfate, lead sulfide oriron oxide, as desired.

These emulsions are excellent high pressure lubricants, and high ratesof bit penetration with long life of bit bearings are obtained in wellsdrilled with the use of this fluid. Heaving shale and other strata ofeasily bydratable earth solids are easily penetrated, and penetration ofbeds of salt or anhydrite has substantially no effect upon theproperties of the emulsion. These emulsions will also remain stable atextreme pressures and at temperatures well in excess of 250 degrees F.

ll The following examples are submitted to illustrate spe cific cases ofpreparation and use of the emulsions and concentrated materials of thisinvention and to show the effect of process variables upon the emulsionsand concentrates.

EXAMPLE I.-MANUFACTURE OF CON- CENTRATED PITCH-ADDUCT-TALL OIL SOLUTIONTo separate batches of solution were prepared containing 75 percent of acottonseed pitch, designated as HCSP in the following table, and 25percent of a heavy aromatic naphtha designated in the table as Exosol.The free fatty acid content was about 26.1 percent, as oleic acid. Eachof these batches contained 365 gallons.

Both batches were then adducted with ethylene oxide in the presence ofsmall amounts of potassium hydroxide according to the process describedabove.

The following table is a material balance of the adduction reaction, inwhich the tank compartments, designated as front and back, eachoriginally contained a 365-gallon batch of the pitch-solvent mixture.

1 This tank was not level and sloped away from drain. Tank was cleanedout before HCSP-EtO adduet run in. This undoubtedly accounted for mostof the loss reported above.

The total product of the two batches of adduct was used to prepare apitch-adduct-tall oil concentrate for use in preparation of invertemulsions.

The same heavy aromatic naphtha was used as solvent, and the pitch,adduct and tall oil were dissolved in the naphtha at a temperaturebetween 160 and 170 degrees F. No difficulties were encountered inobtaining solution of the pitch, adduct and tall oil in the naphthaunder these conditions. The following table is a material balance on thepreparation of this concentrate.

Table N 0. 2

Percent by Gallons Wt. of total Pounds (approx) formula In ut material:

ExOsol s3. 5 8,720 1,130 3.0 780 96 30. 5 7, 950 940 33.0 8, 580 1 1,073

Total 26,030 3, 239 Output:

Fifty-nine 55 gal. drums at 440 pounds net 25, 960 3, 210

Pounds unaccounted for 2 70 1 Volume hot 2 Actually a few gallons placedin 60th drum. No'rE.Ooncentrate A weighed approximately 8.1 lbs/gal.

EXAMPLE II An emulsion prepared from the Concentrate A and B given inthe foregoing, was used under very adverse conditions in taking coresand completing a well. This Well was drilled in porous formations whereseveral hundred barrels of lost circulation were anticipated and theapparatus comprised a single gin pole rig; one 6X12 inch pump capable ofrunning either the gun (mud-mixing jet) or the hole, at 450 to 500pounds per sq. inch, but not both; no shale shaker; and a calcichesettling pit that could take only about 200 barrels of mud.

Under these conditions, it was decided to drill 1,550 feet to withinabout feet of the potential production zone with a water base mud andthen replace the aqueous well fluid with an invert emulsion of ourinvention, drill to a point near that at which the upper edge of the payzone was expected to be encountered, and core drill with the emulsionfor 50 additional feet.

At a depth of 1,550 feet, the mud pits were jetted and cleaned out.Sixty barrels of water and 60 bags of salt were added and the saltcontent was checked at 317,000 parts per million. One hundred twentybarrels of 20 to 21 gravity crude oil was added to overlay the saltwater.

Eight 55-gallon drums (about 3,400 pounds) of Concentrate A were addedto the oil. The mixing gun was started While the 8th drum of ConcentrateA was being added. The pump suction was arranged to pick up salt waterfrom the bottom of the pit and the gun was set to drive oil down intothe salt water. The emulsion quickly began to form and twenty 50-poundsacks of Concentrate B were added slowly through a hopper. An invertemulsion formed readily and when freshly prepared, had an electricalstability of 220, a funnel viscosity of at one end of the pit and at theother end, and a fluid loss of 1.5 cc. (oil only).

Drilling was resumed using this invert emulsion as well fluid and after30 feet of drilling, the emulsion was found to be improved. It now hadelectrical stability of 300, funnel viscosity of 180 seconds and a fluidloss of 1.2 cc. (oil only). Four more bags of Concentrate B were thenadded. After thirty feet of additional drilling, the stability was 500,the funnel viscosity was 200 and the fluid loss was 1.2 cc. (oil only).

After drilling 100 feet with the invert emulsion, a trip was made andthe bit was replaced by an 18 foot conventional core barrel, and coreswere cut. The upper part of the first core was shale and the lower partwas found to be an oil-sand (upper-Mirando). A second core was then cutand recovered, and was found to consist of both upper and lower Mirandosands, with a hard limestone streak in the middle of the core. A thirdcore was cut and recovered. This core was found to be all sand, but thebottom part of the core was a hard water sand.

Gamma ray, neutron and induction logs were run and pipe was set with nodifficulties encountered in completion of the Well.

It was obvious that penetration of the emulsion into the cores wasnegligible. The cores were sent to an independent core testinglaboratory for examination and the laboratory reported that for thefirst time it was able to arrive at a correct value for the watercontent of the Mirando sand; a value it had not been able to determinewith any drilling fluid previously used.

EXAMPLE III In order to determine the effect of varying the proportionsof pitch and ethylene oxide in pitch-ethylene oxideadduct, used inConcentrate A, several pitch-adducts were prepared using from A to 2parts of ethylene oxide per part of pitch by weight, and each adduct wasused in the formula for Concentrate A given above. Eighteen pounds perbarrel of Concentrate A containing 25 percent of each of the variouspitch-ethylene oxide-adducts and 9 pounds per barrel of Concentrate B,were added to the preparation of a series of emulsions, and theproperties of these emulsions were determined. The emul- 13 sionscontained equal volumes of diesel oil and saturated salt water. Thefollowing results were obtained:

Table No. 3

Ratio ofpitch to EtO informula 120.25 1:0.5 1:0.75 1:1.1 1:2.0 1:3.0

Stabilities, mlnutes:

5 120 120 120 60 30 30 180 150 150 60 30 30 240 270 180 60 30 Apparentviscosity. 57 57 63 46 Gel strengths (0/ 33/40 32/80 49/37 20/15WeighIted to 12 lb}- ga Stability 240 270 240 90 Apparent viscos- Y 8884 98 81 Gel strengths (0/ 10' 40/92 38/87 57/80 32/23 Added 25 lb/bbl.

bentonite: Stability 210 210 210 180 Apparent viscosity 108 101 112 150Gel strengths (0/ 10 42/99 32/90 41/75 /40 Aged static 16 hrs. at 250F.: Stability 120/180 /300 90/270 30/300 Apparent viscos y 110 112 14088 Gel strengths (0'/ 33/69 38/99 44/98 18/54 Oil breakout, cc 10 15 1015 Concentrate A: Percent PitchzEtO adduct 25 Humko cottonseed pitch 33Tall oil 3 Mobilsol-K 10 Exosol 29 EXAMPLE IV The effect of varying theratio of vegetable pitch to pitch adduct, made by adducting one part ofpitch with one half part per Weight of ethylene oxide, in the formula ofConcentrate A, above, was determined by preparing emulsions from equalquantities of diesel oil and saturated salt water. Each emulsioncontained the equivalent of 11 pounds of vegetable pitch plus pitchadduct, and 6 pounds of Concentrate B per barrel. The following resultswere obtamed:

Table No. 4

[Ratio of HCSP:EtO (1%)] 60 100 110 150 180 210 110 120 150 240 110 150180 210 300 300 Apparent viscosity 38 54 52 78 105 108 Gel strengths0'10 2/3 27/45 30/40 60/70 90/115 88/95 Weighted to 12 lb/ ga Stability150 270 270 360 270 Apparent viscosity 69 80 82 112 150+ Gel strengths(0 l0 2/6 25/70 35/58 83/100 180/180 Added 25 lb./bb1

bentonite: Stability 150 270 270 300 240 Apparent viscosity 82 99 94 128150+ Gel strengths 3/4 23/33 28/35 65/77 121/186 Aged static 16 hrs.

at 250 F.: Stability 150/150 40/130 120/240 60/330 240/300 Apparentviscosity 77 102 123 120 Gel strengths 0 10 7/10 20/34 37/59 65/8563/108 Fluid loss, cc. oil

(30 minutes) 0.2 1. 4 1. 8 2.0 2. 2

1 Inverted.

EXAMPLE V The properties of three cottonseed vegetable pitches weredetermined before and after adducting them with ethylene oxide invarious proportions. It Was found that adduction changed the propertiesof the pitch as shown by the following table:

Table N 0. 5

After adducting with ethylene oxide in weight ratio of 1 part pitch topart EtO Pitch No. 1:

Free fatty acid (as oleic), percent- 33.1 0. 0 Acid value 24. 2 0.7Saponification number 112. 2 106. 9 Unsaponifiable, percent. 24. 5 17. 8Iodine value 103.4 75.0

After adducting with ethylene oxide in weight ratios of pitch: EtO 1Pitch No. 2:

Free fatty acid (as oleic) percent- Acid value Saponification n Iodinevalue Unsaponifiable, perce After adducting With ethylene oxide inweight ratio of 1 part pitch to 95 part EtO 2 1st reactor 2nd reactorbatch batch Pitch No. 3:

Free fatty acid (as oleic), percent 26. 1 4.1 1.9 Acid value 54.4 8.53.7

Pitch numbers 1 and 2 were adducted with ethylene oxide in a LaboratoryScale Reactor.

2 Pitch number 3 was adducted with ethylene oxide in Commercial PlantProduction.

N OTE.-Pil3cl1 numbers 2 and 3 were diluted with a heavy aromaticnaphtha in Weight ratios of 75% pitch and 25% Exosol before beingadducted with EtO. Analyses on these materials were corrected to theactive basis.

EXAMPLE VI Emulsions were prepared containing equal quantities of dleseloil and saturated salt water emulsified by the use of 15 pounds perbarrel of a number of dlfferent cottonseed pitches and 7 pounds perbarrel of magnesium oxlde, in order to test the effect of the acid valueof the emuls1fier on the characteristlcs of the emulsion. The followmgresults were obtained.

Table No. 6

NATX ISTX Sample identification- 25-OSP 5075 1261 55G G-OSP Acid value 153. 9 54. 4 48. 8 32. 5 24. 2 Free fatty acid, percent 29. 6 26. 1 24. 526. 4 33. 1 Saponification value 128. 9 127.1 134.4 139.0 112.2Unsaponifiables, percent 17.9 15.6 20.4 10.8 24. 5 Base Emulsion:

Stabilit 210 150 150 150 150 Apparent viscosity 44 44 39 45 36 Gelstrength (0710).. 10130 13/22 10/15 12/20 1/1 Fluid loss cc. (30

minutes 0.1 0.0 0.1 0.1 0.0 Weighted to 12 lb./gal:

Stability 315 285 255 195 180 Apparent viscosity-.. 93 84 84 71 65 Gelstrengths (0710') 13/31 14/40 8/31 8/29 2/3 Added 251b./bbl. bentonite:Stability 270 240 240 210 160 Apparent viscosity 113 103 91 75 Gelstrengths (0710).. 20/55 18/57 17/56 13/44 2 2 Aged static 16 hrs. at

250 F.: Stability 390/300 330/315 390/285 255/280 255/105 Apparentviscosit 108 109 81 69 Gel strengths (0710). 21/40 23/73 18/46 18/635/13 Fluid loss, cc. (30

min.) 0.0 0. 0 0. 0 0.0 0. 0

1 Acid value determined according to ASTM Designation: D974-55i orDQ664-54 adapted.

1 EXAMPLE v11 In order to compare the efiect of a constant Weight ofvarious quaternary ammonium surfactants on the properties of invertemulsions, a series of emulsions Were made and their properties weredetermined. Each emulsion contained equal volumes of diesel oil andsaturated salt water, 18 pounds per barrel of Concentrate A, and 2pounds per barrel of Concentrate B prepared from different surfactants.The following results were obtained:

Table No. 7

Cationic surfactants Stability, minutes:

5 210 180 180 150 10.. 180 180 150 150 25.. 180 150 180 150 Apparentviscosity. 42 40 36 41 Gel strengths (0710). 3/12 2/3 5/18 2/10 Weightedto 12lb./ga1

Stabilit 330 330 300 330 Apparent viscosity. 65 65 65 64 Gel strength(0710)..- 3/14 2/4 3/10 1/8 Added 25 113/1210]. bentonite:

Stability 210 180 210 240 Apparent viscosity. 77 82 75 77 Gel strength(0710).. 4/25 3 10 3/20 2 19 Aged static 16 hrs. at 250 F Stability300/300 300/330 330/300 330 300 Apparent viscosity. 150 147 137 136 Gelstrength (0710) 70/116 76/128 70/130 72/128 Stabilities, minutes:

5 150 150 210 180 10.. 150 150 210 180 5 150 180 210 150 Apparentviscosity. 38 31 35 30 Gel strengths (0710) 2/10 1 0 2/5 2/5 Weighted to12 lb./gal

Stabilit 300 240 180 240 Apparent viscosity. 59 62 61 61 Gel strengths(0710). 3/5 2/7 2/7 2/8 Added 25 lb./bbl. bentonite:

Stability 180 150 150 150 Apparent viscosity. 81 77 67 76 Gel strengths(0710'). 4 15 3 10 2 10 2 12 Aged Static 16 hrs. at 250 F Stability300/330 20/270 240/270 2 0/270 Apparent viscosity. 13 13 12 122 Gelstrengths (0710') 73/135 07/101 74/108 68/131 DESCRIPTION Cationicsurfactant No.:

4 Lauryl trimethyl ammonium chloride. 6 Palmityl trimethyl ammoniumchloride. 21 Coco trimethyl ammonium chloride. 26 Monotallow trimetllylammonium chloride. 400 1:1 mixture cationic surfactant 26 and 221. 221Dicoco dimethyl ammonium chloride. H226 Dihydrogenated tallow dimethylammonium chloride. 336 Tricaprylyl monomethyl ammonium chloride.

CARBON CHAIN LENGTH Cationic surfactant No.2

21 C C (C predominating). 26 70% C 30% C 221 C -C (C predominating).

H226 70% c 30% C 336 C -C (C predominating).

AVERAGE MOLEC Cationic surfactant No.:

ULAR WEIGHT EXAMlLE VIII The comparative efiect of the use of variousquaternary lowing rcsults were obtained:

Table N 0. 8

Cationic surfactant Base emulsion:

Stability 135 120 135 120 Apparent viscosity 35 35 35 37 Gczl strepgths3G 31 0 0 2/4 1 9 3 7 2 4 l Fluid Loss, l l 4 9 2 3 cc. (30 min. 0.1 0.00.0 0.0 Wei hted to 12 0 O 0 lb. /ga1.: Stability 210 225 225 225 180180 Apparent viscosity 70 70 73 73 Gel strengths 71 64 0 10 3 8 3 123/12 Added 25 lbJbbl. 3 8 4 14 4/7 bentonitc: Stability 195 225 225 195180 180 Apparent viscos ty 80 83 76 77 Gel s/tre ngths 84 80 0 10 3/133/18 3/16 3/13 )2 Aged static 16 hrs. 7 4 3/10 at 250 F.: Stablllty300/240 270/225 285/240 285/255 255/225 225/210 Apparent viscosity 70 7874 79 Gel s/trengtlls 80 A 0 l0 5/20 3 14 4 14 3 17 F1(111(110SS,)1 cc.l l g 26 4/11 30 min. 0. 0 0. 0 0. 0 0. 0 1. Aged static 47 hrs. 0 0' 0at 300 F.: Stability 90/165 90/150 60/135 Apparent viscosity 73 70 "0G121 sltre rigths t 0 10 0 30 7 2" 4 1 Fluidloss, cc. u l 6 h (30min.) 1. 4 1. 8 1.0 Aged statlc 16 hrs.

stailboiilw F.:

a 'ity 1'0 Gel sltreglgths I d l O 10 4 l8 4 1G 4 20 Fluid loss, cc. l(30 min.) 2.0 1.8 2. 4 Apparent;

viscosity 75 77 70 1 Fluid Loss shown above is oil.

1 7 DESCRIPTION OF' QUATERNARY AMMONIUM SURFACTANTS IN TABLE NO. 8

Cationic surfactant No.2

Myristyl trimethyl ammonium chloride.

7 Stearyl trimethyl ammonium chloride.

15 Oleyl-linoleyl trimethyl ammonium chloride.

21 Coco trimethyl ammonium chloride.

205 Dimyristyl dirnethyl ammonium chloride.

207 Distearyl dimethyl ammo nium chloride.

18 Table No. 10

INITIAL PROPERTIES 1 Sample appeared to be much thicker than indicatedon meter. Rotor probably slipping through this grease-like substance andnot indicating true viscosity.

Table No. 9

20 Gel on Solid used parent Vis- Yield strength break- Settling Cationicsurfactants ig coslty point (0 I10) out 21 221 721 26 726 336Attapulgite 47 20 54 10/10 Trace None. 3 25 Wyoming Base emulsionblentonite 33 20 26 16/20 53100.1 dNone. Stability l 120 155 120 105 105120 Ta 0 16 16 0 fled g ig; Apparent viscosi y 37 39 Gel s/tlroe ngths4/ 4/ 1 2110 1 5538}; 0 0 0 0 3O 30 nutes weilggitedlto 12 7 EXAMPLE X eStability 195 180 195 150 180 180 High temperature-high pressure fluidloss ChaIHCtCHStICS ggfiiffjf: of emulsions prepared from equal volumesof oil and Gel strengths saturated salt water by the use ofthecombination of Added Concentrate A and B Were determined, and compared 8bsgntonite 21 195 195 120 150 with the results obtained by the add1t1onof flllld loss pre- 0 venting materials to the emulsion. The followingresults oosity 68 80 6 61 72 were obtained: Gel strengths 3 75 105 00135 150 75 150 45 105. Table 11 8/23 3/11 6/21 4/12 2,4 45 Emulsifiers212 F. Fluid loss} cc. 2 5 4 3 1 5 30 in. 0.0 0.1 1.0 0.8 I mConcentrate A,

lb/bbl 1s 24. 1s 0 18 1s 1 The fiuid loss shown is oil unless otherwisespecified. i f? 6 9 9 9 9 6 a Water Other agents, 11)] Quaternaryammonium surfactant: 1 250 F 21 Coco trimethyl ammonium chloride. 221Dicoco dimethyl ammonium chloride. 55 gg gg 18 18 721 N-coco,NI-N-dimethyl, N-N-N'-trig ggggf 1 1 lb 6 a methyl 1, 3 propylenedlammoni O ther agents, 1b um chloride. bbi 5 26 Tallow trimethylammonium chloride.

' I I I 726 N-tallow, N,N-d1methyl, N EN -N -tr 1- Base emulsion 2120 Rmethyl-1, 3-propylene mammom- 36 T P th 1 tabnnyl 105 255 100 go 240 2353 ncapry y monome y ammonium ppa nt vis sity- 64 55 53 2 73 78 Gelstrength (0710). 35/49 30/35 27/32 1/3 53 5s 46- chlonde- Fluidloss,oil,cc. at l 500 p.s.i.g 1.4 0.5 1.8 1.0 0.0 1.0 EXAMPLE IX 250 F Theeiiects of attapulgite, Wyoming bentonite and talc 5 Stability 195 2851n thickening diesel oil Was compared with mixtures of Apparentviscositl 64 78 300 cubic centimeters of diesel oil with 72 grams ofsolid f th (0 35/49 46/- material for a period of five minutes on aHamilton Beach 21:? L 8 L1 mixer at 110 volts, followed by theintroduction of 36 grams of coco trimethyl ammonium chloride andcontinu- 1 oleic acid ing mixing for twenty-five additional minutes. Thefol- Qg g e lowing results were obtained.

4 Jet Gilsonite.

EXAMPLE XI Table No. 13

The lubricating properties of emulsions prepared with M fa t AConcentrates A and B were determined by preparing 11 one-barrelequivalents of emulsion in the manner de- 5 calcined magnesite NO 5 1530 scribed above using equal volumes of diesel oil and saturated saltwater. Eighteen pounds per barrel of Concen- Bulk denslty (1b it 60 2824 8 5 trate A and 6 pounds per barrel of Concentrate B were Iodinevalue10-18 25-40 used as emulsifiers. The following results were obtained: 10lbjbbL Mgo m used 7 7 7 7 Stabilities, min.: Table N 12 5 150 135 135120 12 442 125 122 a: EXTREME PRESSURE LUBRICATING PROPERTIES OF Aar'fii'ish y 91 45 43 44 EMULSIONS PREPARED WITH CONCENTRATES A 15 g0)-- 56 53 25 32 3 5 13 25 AND B Fluid loss (55.) }2.5(0. 2.0(E.) 1.s 0.

Aged static 64 hrs. at 250 F.: The emulsion had the following initialproperties: t bility, 130 70 150 90 180 00 270 fi f i 101 7 171% 24/3724/22 e reng 3 Electrical Volts 240 Fluid loss 55. 1.3m. 1. 5 0. 1.s 0.1.2 o. Apparent viscosity, cps 51 20 I I Gel Strength (0 /10 20/27Manufacturer B Manufacturer A After the emulsion had aged at roomconditions for 5 approximately 20 hours, its extreme pressurelubrication gfg maguesitc y gg MgCOa tg- Mg004 e H)z properties weremeasured on a No. 1750 Timken Lubri- 25 cant Tester. The followingresults were shown from these Bulk denslty 2M5 5 20 5 tests: Iodinevalue (m1. eq./100 gm.).. 1-14 15-25 10-18 15-25 Lb./bb1. M o, etc. used7 7 7 14 15 Stabilities, minutes:

5 120 165 105 135 210 170 Tempew- A t 4 2% 33 Z2 Z3 33 pparen VlSCOSl yLoad Time 35 Gel Strength 0 10 24/38 50 59 40 50 78 48/02 Test No.Results Fluid loss (cc.) 2. 0 0. 2.2 o. 1.s(0. 2.4 o 2.4 0.

. Aged static 64 hrs. Inlt1al Final at 5 F.

Stability 120/180 75/120 60/135 75/180 120/210 Apparent viscos- 78 ity40 55 41 50 as 91 116 10 40 Gel strength 94 124 (0 0' 18/34 25 41 12 2421/48 32/51 122 153 Fluid loss 414 1. 8(0.) 2.s(o. 20 0 1 4 0. 2.s 0.

Sear Power (kw.)

Test No.

Width Nature Max. Min. EXAMPLE XIII (mm.)

D t i 0 95 0 42 Invert emulsions were prepared from equal volumes of i;fj3j fjffff diesel oil and saturated salt water using 30 pounds of Con-4.s Sngm tnbu 1 0- centrate A and 15 pounds of Concentrate B per barrelof g on 50 emulsion. One pound of sodium hydroxide per barrel of 4.9---.do 1.85 70 emulsion was added to a part of the emulsion, the twosamples then being weighted by addition of barium sulfate and aged foran equal length of time under identical conditions to determine theeffect of aging. The following results were obtained:

Properties of emulsion after test: Table No 14 Electrical stability,volts 270 vlscosl'ty apparent cPs 80 Other agents (lb./bbl1) None lNaOH(O'/ 10) gel strength 42/63 Fluid loss, cc. oil, 7 /2 min 0.1 Base611111151011;

Stability 300 330 3 11 1111311 8? 29 25 2 e s reng EXAMPLE XII Weightedto 121b/gal:

Stability 315 300 Apparent viscosity. 107 82 The effect of differentphysical propert1es of calcined gelst1rengili11(0/10% 2 46/85 5/14magesite, magnesium carbonate and magnesium hydroxide g fjjffff 50 0/3000/255 on the properties of invert emulsions was studied on samappa 27/472 ples of emulsions prepared from equal quantities of diesel 56235 81 1oil and saturated salt water, emulsified with 18 pounds g g gz g g (9 0.t) gig per barrel of Concentrate A and 7 pounds per barrel of e mgo an epercen m magnesium compound. The following table lists the re- 1 onsults obtained: 75 2 Hag/1 settling 21 EXAMPLE XIV One thousandthirty-three barrels of the invert emulsion well fluid of this inventionwere prepared for experimental use in a well. In addition to the usualqualities desirable in Well fluids, it was found that these invertemulsions had extremely high lubricity.

Since the equipment used for the preparation of this material consistedof one 100-barrel tank with three mixing guns, having one-half inch jetnozzles, the following procedure was used:

(1) Fifty-seven barrels of 32 gravity diesel oil were introduced intothe tank.

(2) Four drums of Concentrate A, described above, were added to thediesel oil and thoroughly mixed for a period of about to minutes.

(3) Fifteen barrels of salt water containing about 250,000 parts permillion of salt were added and mixing was continued with pump pressureat 500 p.s.i. for 30 minutes.

(4) Fifteen additional barrels of salt water were added and mixed for 30minutes.

(5 Eight 50-pound sacks of Concentrate B were added and mixed forminutes.

(6) Seventy-five sacks of barite were added to obtain the desired mudweight and the whole was mixed for a period of 2 hours.

The final volume of materials introduced was as follows:

Barrels Diesel oil 57 Salt water 30 Concentrate A 5 A Concentrate BBarite 5 The total volume of this mixture of materials was 97.5 barrels.Similar procedures were employed until the required amount of invertemulsion was prepared.

At this time the Well had a depth of 6,657 feet. Twenty barrels ofdiesel oil were introduced into the drill pipe ahead of the invertemulsion to act as a cushion between the emulsion and the Well fluid indrilling to this depth. One hour was required to displace the previouslyused drilling fluid and approximately 575 barrels of invert emulsionwere required for this displacement. The viscosity of the invertemulsion Was a bit high after the first circulation and 40 barrels ofdiesel oil were added and mixed very thoroughly therewith to reduce theviscosity. The well Was drilled 1,729 feet deeper in very hard formationand under drilling conditions so dflicult that a total of 17 drill hitswere used in penerating through the 1,729 feet of hard formation. It wasobserved that all drill hits were well Worn with thoroughly dulledteeth, but the bearings on all bits brought to the surface for changeswere found to be in good condition due to the very high degree oflubricity of the mud. The average rate of penetration was 16 feet perhour, which is exceptionally high for this particular type of formationand a representative of the major oil company believes it to be thehighest rate of penetration ever attained. The Well hole remained verystable and apparently in gage throughout the drilling. The mud remainedremarkably stable even though the mixing pressure was low and at a depthof 8,314 feet, the mud had a funnel viscosity of 100 seconds per quart,weight at 74 pounds per cubic foot, gel strength at 5/20, stability at220 and contained 57 percent oil, 33 percent water, and 10 percentsolids.

From the foregoing it will be seen that this invention is one welladapted to attain all of the ends and objects hereinabove set forth,together with other advantages Which are obvious and which are inherentto the process and composition of matter.

It will be understood that certain features and subcombinations are ofutility and may be employed without reference to other features andsubcombinations of the invention. This is'contemplated by and is withinthe scope of the claims.

As many possible embodiments may be made of the invention, withoutdeparture from the scope thereof, it is to be understood that all matterherein set forth is to be interpreted as illustrative and not in alimiting sense.

The invention having been described, what is claimed is:

1. An invert emulsion Well fluid comprising about 10 to volume percentof an aqueous phase dispersed in about 90 to 10 percent of oil phase; apolymerized polybasic fatty acid pitch, and an adduct made by adductingpolymerized polybasic fatty acid pitch with about A to its weight ofethylene oxide, in proportion equivalent to about 5 to 75 percent of thetotal weight of the pitch and adduct, said pitch and adduct beingpresent in quan tity sufiicient to emulsify the phases; tall oil to aneX- tent of about 5 to 10 percent of the total Weight of pitch andadduct; a basic material selected from the group con sisting ofmagnesium oxide, magnesium hydroxide and magnesium carbonate, inquantity suflicient to form soaps with all free fatty acids present; andabout 0.03 to 1.6 pounds per barrel of a salt of a tetra alkylsubstituted ammonium radical in which at least one of the alkyl groupsis a hydrocarbon residue of a fatty acid having from 8 to 18 carbonatoms per molecule adsorbed on about 4 to 8 times its Weight ofattapulgite.

2. The well fluid of claim 1 wherein the aqueous phase consistsessentially of sea water.

3. The well fluid of claim 1 wherein the aqueous phase comprises anaqueous drilling mud.

4. An invert emulsion Well fluid comprising about 30 to 70 volumepercent of aqueous phase dispersed in about 70 to 30 percent of oilphase and containing about 5 to 8% pounds per barrel of polymerizedpolybasic fatty acid pitch; a pitch-adduct made by adducting the pitchwith 40 to 60 percent of its Weight of ethylene oxide, said adduct beingpresent to the extent of about 25 to 50 percent of the total Weight ofpitch and adduct; tall oil in quantity from 5 to 10 percent of the totalweight of pitch and adduct; about 0.75 to 15.5 pounds per barrel ofmagnesium oxide; and about 0.03 to 1.6 pounds per barrel of a salt of atetra alkyl substituted ammonium radical in which at least one of thealkyl groups is a hydrocarbon residue of a fatty acid having from 8 to18 carbon atoms per molecule in intimate admixture with about 4 to 8times its weight of attapulgite.

5. An invert emulsion well fluid comprising about 30 to 70 volumepercent of salt water phase dispersed in about 70 to 30 percent ofpetroleum oil phase and containing about 5 to 10 pounds per barrel ofpolymerized polybasic fatty acid pitch; a pitch-adduct made by adductingthe pitch with about A to its Weight of ethylene oxide, said adductbeing present in proportion to furnish about 5 to 7-5 percent of thetotal Weight of pitch and adduct; tall oil in an amount equivalent toabout 5 to 10 percent of the total weight of pitch and adduct; magnesiumoxide in quantity at least suflicient to form magnesium soaps with allfatty acids present; about 0.03 to 1.6 pounds per barrel of a materialselected from the group consisting of lauryl trimethyl ammoniumchloride, palrnityl trimethyl ammonium chloride, coco trimethyl ammoniumchloride, monotallow trimethyl ammonium chloride, dicoco dimethylammonium chloride, dihydrogenated tallow dimethyl ammonium chloride,tricaprylyl monomethyl ammonium chloride, myristyl trimethyl ammoniumchloride, oleyl-lineoleyl trimethyl ammonium chloride, stearyl trimethylammonium chloride, dimyristyl dimethyl ammonium chloride, and distearylammonium chloride, in intimate admixture with about 4 to 8 times itsweight of attapulgite.

6. An invert emulsion well fluid comprising about 30 to 70 volumepercent of a salt water phase dispersed in about 70 to 30 percent ofrefined petroleum oil phase and containing about 5 to 8 /4 pounds perbarrel of vegetable pitch; a pitch-adduct made by adducting the pitchwith about 40 to 60 percent of its Weight of ethylene oxide, said adductbeing present in proportion of about 25 to 50 percent of the totalweight of pitch and adduct; tall oil in an amount corresponding to aboutpercent of the total weight of pitch and adduct; about 0.75 to 30.0pounds per barrel of magnesium oxide; and about 0.03 to 1.6 pounds perbarrel of a material selected from the group consisting of lauryltrimethyl ammonium chloride, palmityl trimethyl ammonium chloride, cocotrimethyl ammonium chloride, monotallow trimethyl ammonium chloride,dicoeo dimethyl ammonium chloride, dihydrogenated tallow dimethylammonium chloride, tricaprylyl monomethyl ammonium chloride, myristyltrimethyl ammonium chloride, oleyl-lineoleyl trimethyl ammoniumchloride, stearyl trimethyl ammonium chloride, dimyristyl dimethylammonium chloride, and distearyl ammonium chloride in intimate admixturewith about 0.15 to 6.0 pounds per barrel of attapulgite.

7. An invert emulsion well fluid comprising about 30 to 70 volumepercent of a salt water phase dispersed in about 70 to 30 percent ofrefined petroleum oil phase and containing about 5 to 8% pounds perbarrel of vegetable pitch having a free fatty acid content of at least23 percent; a pitch-adduct made by adducting the pitch with aboutone-half its Weight of ethylene oxide, said adduct being present inproportion of about 5 to 75 percent of the total weight of pitch andadduct; tall oil in an amount equivalent to about 5 to percent of thetotal Weight of pitch and adduct; about 0.75 to 15.5 pounds per barrelof magnesium oxide; and about 0.035 to 0.4 pound per barrel of cocotrimethyl ammonium chloride in intimate admixture with about 0.15 to 3.0pounds per barrel of attapulgite.

8. A process for preparing an invert emulsion Well fluid which comprisesintroducing a petroleum oil, a polymerized polybasic fatty acid pitch,an adduct made by adducting the pitch with from A to /4 its weight ofethylene oxide, tall oil, water, a basic material selected from thegroup consisting of magnesium oxide, magnesium hydroxide, and magnesiumcarbonate, and a salt of a tetra alkyl substituted ammonium radical inwhich at least one of the alkyl groups is a hydrocarbon residue of afatty acid having from 8 to 18 carbon atoms per molecule in intimateadmixture with 4 to 8 times its weight of attapulgite into anemulsification zone; controlling the quantities of materials introducedso that a resulting emulsion contains from 10 to 90 volume percent ofaqueous phase dispersed in 90 to 10 percent of oil phase, pitch andpitch-adduct in amounts sufiicient to emulsify the phases, the ratiobetween pitch and pitch-adduct is in the range from 5 to 75 percent ofthe total weight of pitch and adduct, the weight of tall oil is in therange from 5 to 10 percent of the total weight of pitch and adduct, theproportion quaternary ammonium surfactant is in the range from 0.03 to1.6 pounds per barrel of finished emulsion; the basic magnesium materialis introduced in quantity at least suflicient to form magnesium soapwith all free fatty acids present; and agitating said materials in theemulsification zone until an invert emulsion is formed.

9. A process for preparing an invert emulsion well fluid which comprisesintroducing salt water into an emulsifying zone in quantity sufficientto form 30 to 70 volume percent of an emulsion to be produced; thereinoverlaying said water with suificient petroleum oil to form 70 to 30volume percent of oil phase in said emulsion; adding to and dissolvingin said petroleum oil a polymerized polybasic fatty acid pitch inquantity to give from 5 to 10 pounds per barrel of finished emulsion, apitch-adduct, made by adducting the pitch with about A to its weight ofethylene oxide, in proportion to furnish about 5 to 75 percent of thetotal weight of pitch and adduct, tall oil in an amount equivalent toabout 5 to 10 percent of the total weight of pitch and adduct; agitatingthe water and oil until an emulsion begins to form; and continuingagitation while adding magnesium oxide in quantities at least sufiicientto form magnesium soaps with all free fatty acids present and about 0.03to 1.6 pound per barrel of finished emulsion of a salt of a tetra alkylsubstituted ammonium radical in which at least one of the alkyl groupsis a hydrocarbon residue of a fatty acid having from 8 to 18 carbonatoms per molecule in intimate admixture with about 4- to 8 times itsweight of attapulgite.

10. A process for producing an invert emulsion well fluid whichcomprises introducing into an emulsifying zone a sutlicient quantity ofwater to form from 10 to 90 volume percent of an aqeuous phase in anemulsion to be produced; introducing upon the Water in said emulsifyingzone a petroleum oil in quantity to form from 90 to 10 volume percent ofan oil phase; mixing with the petroleum oil an effective amount of anemulsifier solution containing a vegetable pitch, a pitch-adduct made byadducting the pitch with A to its weight of ethylene oxide, said adductbeing present in proportion of about 25 to 50 percent of the totalweight of pitch and adduct; tall oil in proportion from about 5 to 10percent of the total weight of pitch and adduct and an'oil misciblesolvent in quantity sufficient to dissolve said pitch, adduct and talloil; agitating the oil and Water; and adding as an emulsion forms a saltof a tetra alkyl substituted ammonium radical in which at least one ofthe alkyl groups is a hydrocarbon residue of a fatty acid having from 8to 18 carbon atoms per molecule in intimate admixture with from 4 to 8times its weight of attapulgite and magnesium oxide in quantity at leastsufiicient to form magnesium soaps with all free fatty acids present.

11. A process for producing invert emulsion well fluid which comprisesintroducing sufiicient quantity of Water into an emulsifying zone toform from 10 to 90 volume percent of aqueous phase in a resultingemulsion; introducing a quantity of a petroleum oil sufficient to formfrom 90 to 10 percent of an oil phase in an emulsion into theemulsifying zone upon said water; mixing with said petroleum oil from to25 pounds of emulsifier solution per barrel of emulsion, said solutioncontaining about 33 percent vegetable pitch, about 25 percent of apitch-adduct made by adducting the pitch with from A to %1 its Weight ofethylene oxide, about 3 percent of tall oil, and about 39 percent of aheavy aromatic naphtha; agitating the oil and water in the emulsifyingzone until an emulsion begins to form; adding thereto from 1 to poundsper barrel of a dry-free-flowing powder containing about 3.5 to 4.0percent of a salt of a tetra aikyl substituted ammonium radical in whichat least one of the alkyl groups is a hydrocarbon residue of a fattyacid having from 8 to 18 carbon atoms per molecule in intimate admixturewith about 15 percent of attapulgite and about 77 percent of magnesiumoxide; and continuing agitation of the oil and Water until an invertemulsion is formed.

12. The process of claim 11 wherein from 17 to pounds per barrel of thepitch-adduct-tall oil solution is added to the oil and about 12 to 20pounds per barrel of the dry free-flowing powder is added duringagitation.

13. A concentrated emulsifying material for producing invert emulsionwell fluid which comprises a vegetable pitch; a pitch-adduct made byadducting the pitch With about A to its weight of ethylene oxide, saidadduct being present in proportion of about 25 to percent of the totalweight of pitch and adduct; tall oil in proportion of about 5 to 10percent of the total weight of pitch and adduct; and sufficient oilmiscible solvent to maintain the pitch-adduct and tall oil in solution.

14. A concentrated emulsifying material for the production of invertemulsion Well fluid which comprises about 33 percent of vegetable pitch,about 25 percent of a pitch-adduct made by adducting the pitch withabout 25 to percent of its weight of ethylene oxide, about 3 percent oftall oil, and about 39 percent of a heavy aromatic naphtha.

15. A process for the recovery of cores in substantially native statewhich comprises introducing into a well an invert emulsion well fluidcontaining about 10 to 90 percent of aqueous phase dispersed in from 90to 10 percent of oil phase and further containing per barrel of emulsionabout to 8% pounds of vegetable pitch, and about 3 to 6% pounds ofvegetable pitch-adduct made by adducting the pitch with about A to itsweight of ethylene oxide, about 0.4 to 0.75 pound of tall oil, about0.034 to 0.7 pound of a salt of a tetra alkyl substituted ammoniumradical in which at least one of the alkyl groups is a hydrocarbonresidue of a fatty acid having from 8 to 18 carbon atoms per molecule inintimate admixture with about 0.15 to 3.0 pounds of attapulgite, saidemulsion further containing magnesium oxide in quantity at leastsufiicient to form magnesium soaps with all free fatty acids present;cutting a core from a stratum in the presence of said invert emulsionwell fluid and removing the core from the well.

16. A process for the rotary drilling of wells which comprisesintroducing into a well an invert emulsion well fluid of high lubricitycontaining from about 10 to 90 percent of aqueous phase dispersed infrom about 90 to 10 percent of oil phase and further containing about 5to 8% pounds of vegetable pitch per barrel of emulsion, and about 3 to6% pounds of vegetable pitch-adduct made by 26 adducting the pitch withabout A to its weight of ethylene oxide, about 0.4 to 0.75 pounds oftall oil, about 0.034 to 0.7 pound of a salt of a tetra alkylsubstituted ammonium radical in which at least one of the alkyl groupsis a hydrocarbon residue of a fatty acid having from 8 to 18 carbonatoms per molecule in intimate admixture With about 0.15 to 3.0 poundsof attapulgite, said emulsion further containing magnesium oxide inquantity at least suflicient to form magnesium soaps with all free fattyacids present; rotary drilling in the presence of said invert emulsionat a high rate of bit penetration; and lubricating moving parts in saidwell for a high degree of lubricity provided by said fluid.

References Cited in the file of this patent UNITED STATES PATENTS

1. AN INVERT EMULSION WELL FLUID COMPRISING ABOUT 10 TO 90 VOLUMEPERCENT OF AN AQUEOUS PHASE DISPERSED IN ABOUT 90 TO 10 PERCENT OF OILPHASE; A POLYMERIZED POLYBASIC FATTY ACID PITCH, AND AN ADDUCT MADE BYADDUCTING POLYMERIZED POLYBASIC FATTY ACID PITCH WITH ABOUT 1/4 TO 3/4ITS WEIGHT OF ETHYLENE OXIDE, IN PROPORTION EQUIVALENT TO ABOUT 5 TO 75PERCENT OF THE TOTAL WEIGHT OF THE PITCH AND ADDUCT, SAID PITCH ANDADDUCT BEING PRESENT IN QUANTITY SUFFICIENT TO EMULSIFY THE PHASES; TALLOIL TO AN EXTENT OF ABOUT 5 TO 10 PERCENT OF THE TOTAL WEIGHT OF PITCHAND ADDUCT; A BASIC MATERIAL SELECTED FROM THE GROUP CONSISTING OFMAGNESIUM OXIDE, MAGNESIUM HYDROXIDE AND MAGNESIUM CARBONATE, INQUANTITY SUFFICIENT TO FORM SOAPS WITH ALL FREE FATTY ACIDS PERSENT; ANDABOUT 0.03 TO 1.6 POUNDS PER BARREL OF A SALT OF A TETRA ALKYLSUBSTITUTED AMMONIUM RADICAL IN WHICH AT LEAST ONE OF THE ALKYL GROUPSIS A HYDROCARBON RESIDUE OF A FATTY ACID HAVING FROM 8 TO 18 CARBONATOMS PER MOLECULE ABSORBED ON ABOUT 4 TO 8 TIMES ITS WEIGHT OFATTAPULGITE.